1. Technical Field
This invention generally relates to air spring assemblies and, more particularly, to a spacer for the piston or bead plate of an air spring assembly. Specifically, the invention relates to a non-metallic spacer for the piston or bead plate of an air spring assembly with the spacer having structure that provides strength in a variety of mounting configurations and a hole pattern that accepts a variety of air spring assemblies.
2. Background Information
Pneumatic assemblies such as air actuators and springs have been used for many years for various purposes. The air actuator usually includes a flexible rubber sleeve or bellows containing a supply of pressurized fluid and a feed for increasing or decreasing the pressurized fluid therein. The flexible sleeve is formed of a flexible elastomeric material often containing reinforcing cords, where the flexibility of the material permits a first end cap to move axially with respect to another end cap secured within the ends of the sleeve as the amount of pressurized fluid is changed. When the air actuator is positioned between a movable or actuatable object and typically a fixed object, the movable object moves in correlation to the axial movement of the end caps.
As to pneumatic springs, commonly referred to as air springs, the construction is similar with a flexible rubber sleeve or bellows containing a supply of a pressurized fluid. The air spring is different in that it has one or more pistons movable with respect to the flexible sleeve. The piston causes compression and expansion of the fluid within the sleeve as the sleeve stretches or retracts, respectively, thereby absorbing shock loads and/or dampening vibrations. The flexible sleeve is formed of a flexible elastomeric material that typically contains reinforcing cords. The structure of the sleeve permits the piston to move axially with respect to another piston or end cap secured at the other end of the sleeve. One application for such air springs is with motor vehicles where the spring provides cushioning between movable parts of the vehicle, primarily to absorb shock loads impressed on the vehicle axles by the wheel striking an object in the road or falling into a depression.
One problem with air spring assemblies is that they must be provided in a wide variety of shapes and sizes to fit the numerous suspension system configurations that are known in the art. As such, the air spring manufacturer is forced to provide each air spring configuration in a variety of heights and diameters so that each suspension application falls within the design envelope of at least one air spring assembly. It is thus desired in the art to provide spacers that may be combined with air spring assemblies to expand the design envelope of the air spring assemblies. Spacers allow the design height, minimum height, maximum height, and stroke of an air spring assembly to be easily modified. The spacers thus allow the manufacturer to decrease the total number of air spring configurations in its inventory and manufacturing line. It is thus desired in the art to provide an improved spacer for an air spring assembly that performs these functions.
Prior art spacers have been fabricated from a metal that is typically aluminum or steel. One problem of fabricating spacers from metal is the overall expense associated with casting or forming the metal spacer. Another problem is the weight of the metal spacers. A further problem is that the spacers are subject to harsh environmental conditions that lead to corrosion of metal spacers. It is thus desired in the art to provide a lightweight, non-corrosive spacer.
A problem in the art with manufacturing spacers for air spring assemblies out of lightweight non-corrosive materials such as plastic is that the spacers are subjected to significant forces during use. The spacers also must be designed with a safety factor because they are used in vehicle suspensions. A specific problem related to the strength of the spacer occurs in partial-beam mounting arrangements where the spacer is not entirely supported by a suspension member such as when the spacer extends out over the edge of a suspension member. It is thus desired in the art to provide a non-metallic spacer that is strong enough to withstand the operating environments of an air spring assembly.